The present invention relates to managing multicast router ports in a Layer 2 (L2) network, and more particularly, this invention relates to fast recovery of multicast router ports on spanning tree protocol (STP) topology change in a L2 network.
In a L2 network, for multicast traffic with Internet Group Management Protocol (IGMP) version 3, according to Internet Engineering Task Force (IETF) Request For Comment (RFC) 3376, there is no existing method or mechanism in place or described to recover multicast router ports in an expedited manner. As a result, upon a STP topology change, multicast traffic may take multiple minutes to recover. This loss of multicast traffic for such a prolonged time period may result in significant information loss in the L2 network.
Several known solutions to recover multicast traffic quickly in an IGMP snooping network include the following procedures: a) flooding multicast traffic for a few minutes (or longer) after a STP topology change; b) sending IGMP general queries with source=0.0.0.0; and c) lowering the IGMP query interval to 15 seconds. However, each of the above known solutions have drawbacks, specifically that solution a) unnecessarily floods traffic on the network, and specifically on a virtual local area network (VLAN) specified by the multicast traffic, solution b) does not completely solve the problem and leaves another problem to be solved, and solution c) is not scalable, and therefore is ineffective in large scale and/or distributed network systems.